DURHAM -- Mike Krzyzewski didn’t have any Duke basketball players on the U.S. Olympic team that he led to the gold medal in London this summer.

But while Coach K was earning America its third straight major international championship (following the 2008 Olympics and the 2010 World Championship), three players from his 2011 recruiting class were also overseas, trying to use international competition to hone their games for the coming season.

Sophomore Quinn Cook and redshirt freshman Marshall Plumlee both started for a collection of American college all-stars that competed in the Four Nations Cup in Estonia. Redshirt freshman Alex Murphy was a starter for the Finnish Under 20 National team at the European championships in Bulgaria.

That summer experience could have a major impact on the 2012-13 Blue Devils.

“It helped me a lot,” Cook said of his trip to Estonia. “It helped my confidence -- just to see where I was after my hard work in the spring and the beginning of the summer.”

Cook is still trying to regain the stature he had three years ago before suffering a knee injury. In the summer of 2010, he was regarded as the best point guard in his class – that spring he had beaten out future first-round NBA draft pick Kendall Marshall as the player of the year in Washington, D.C., and that summer he started at point guard for the U.S. Under 18 National team – ahead of future first-round picks Marquis Teague and Tony Wroten.

But he was slowed so much by his knee injury that the Duke staff shut him down last season to get healthy. He missed an entire summer of workouts, including the team’s trip to China and Dubai. By the time he resumed workouts in October, his game was rusty and he spent the entire season trying to catch up with his teammates.

“The hardest part of coming back from an injury is getting there mentally,” Cook said. “I just battled with pains here and there, then I stopped believing in myself because I wasn’t playing. I was not feeling motivated to practice because I wasn’t confident in myself. I wasn’t in the best shape. My teammates never believed in me because they never played with me until the first day of practice.

“Just coming from high school to Duke basketball, this is a whole different level and you need months to prepare. By missing my whole spring and summer and not preparing was definitely a setback. That’s what’s motivated me this summer and last spring.”

Cook credits the Estonia trip with helping to restore his confidence.

“Coach [Guy] Ramcourt told me that it was my team and he wanted me to control everything,” Cook said. “He basically had a lot of trust in me. It was just a pleasure to be over there and represent your country. All in all, it did a lot for my confidence.”

The Duke sophomore averaged 22.0 points and 4.0 rebounds in the three-game tournament. More importantly, he found the shooting touch that deserted him last season (when he hit just 40.5 percent), hitting 51.1 percent from the floor.

“I didn’t have any confidence in my jumper last year,” he said. “I went through a little slump. Percentage-wise, I was horrific. I got a lot of criticism. That’s just motivation. I’ve been shooting a lot this summer and this fall, getting a lot of jumpers in. That’s one of the strongest parts of my game. The biggest thing was shooting with confidence. In Estonia, my jumper was falling because I had confidence in myself.”

Cook expects to use his summer experience to challenge for Duke’s starting point guard job this season.

“This summer was reassuring for me,” he said. “Both the Nation’s Cup and the Pro Am … playing basketball again … working on my game during those games … and seeing where I was at. I performed well. I needed that, just for confidence. I know it’s not the ACC, but I feel good where I am. I feel good about what I contribute to the team.”

That feeling was shared by his teammate in Estonia, Marshall Plumlee. The 6-11 center hasn’t played competitive basketball since the spring of 2011, when he led the Christ School in Arden, N.C., to the state private school championship.

The youngest of the three Plumlee brothers to play at Duke, Marshall said he used his redshirt year to get bigger (up to 240 from 220) and stronger.

“One of the biggest differences is being able to hold my space better in the low post as well as being able to finish better through contact,” Plumlee said. “The college game being more physical than the high school game, that’s an adjustment I had to make. Those are steps I needed to take. I need to continue working on my size, my speed and my explosiveness.”

Plumlee started at center for the American all-stars in the Four-Nation’s Cup, averaging 7.7 points, 8.3 rebounds and 3.0 blocked shots a game.

Cook said that was an impressive performance against the competition they faced.

“We were playing against grown men,” he said. “Everybody was a pro. You had about four or five guys from each team that had NBA experience. They were grown men with bills and families to feed. It was great experience for me and Marshall to get out there.”

The competition might have been older and more experienced, but Plumlee didn’t feel overmatched.

“I felt like I was on a level playing field with anybody we went up against physically, in terms of size and strength and speed,” he said. “I actually felt like I had an edge athletically. That gave me confidence. My development from last year to this year – last year, that wouldn’t have been the case.”

While Cook and Plumlee were playing in Estonia, Alex Murphy was leading the Finnish National team in Bulgaria. He qualified for the team, through his mother, a native of Finland.

“Mother played professionally in Sweden when she was young,” he said. “She played some years with the [Finnish] national team.”

Murphy was looking for the competition after sitting out last season, just as Marshall Plumlee did. He had arrived at Duke a year ahead of his class after graduating from high school early and skipping his final year at South Kingstown High School in Rhode Island.

He came expecting to redshirt in 2011-12, but his strong play during the China trip and in preseason practice almost changed that plan.

“Initially, when I was still in high school and decided that I was going to come early, my first thought was, ‘Okay, I’m leaving high school early and going down to a place like Duke, I probably will redshirt’,” he said. “I thought that was the best thing for me. But with the summer I had and the trip overseas last summer and how I progressed in the fall, the idea sort of slid out the window and they said ‘You’re ready to play … you can play this year.’

“That gave me a lot of confidence going into the year.”

But Murphy suffered a concussion in practice before the opener and with the layoff that entailed, he and the staff decided to go ahead with the original plan.

“Looking back, it’s something that I probably could have recovered from,” he said. “I feel like I could have earned a spot in the lineup and played. But sometimes things happen like that and it’s a blessing in disguise. That happening wasn’t good, but looking back on it, it could have been one of the best things that ever happened to me.”

Murphy was rated one of the top 10-15 prospects in his class as a prep junior. By coming to Duke early, he gave up the chance to win a bunch of prep All-America honors.

“That’s one thing I learned when I got here – when you are in high school, the rankings and ratings and all that stuff – the McDonald’s All-America game, the Jordan-Brand Classic – that’s like the most important thing to you,” he said. “But as soon as you set foot on a college campus, to be honest, none of that stuff matters.

“I sometimes think about what would have happened if I had stayed in high school, but I think that coming down here early and going through redshirt year was by far the best thing I could have done for myself. Not even close.”

Still, Murphy admits that he got a little restless watching from the sidelines all season.

“It was tough, especially during the ACC and NCAA Tournaments – I had never not played for that length of time,” he said. “That’s when it started to hit me. But right about the time our season ended, that was when I got the news that I would be playing for Finland.”

Murphy spent almost a month overseas, playing four exhibitions before the actual Under-20 Championships.

“We played four games – one in Finland and three in Serbia … sort of exhibition games,” he said. “Those were the best games I played over there. I played well in the tournament as well, but the first game over there was like a showcase. We played an exhibition against Estonia, right in the capital of Finland, Helsinki, where we had our training camp. I scored 36 points and had nine rebounds. That was just a few days after getting there, so that was a big deal for everybody over there.

“That was a good way to start the trip.”

Murphy averaged over 25 points in the team’s four exhibitions. It was obvious that he was the best player on the team.

“At times, I played every position … I played point,” he said. “We were a little undersized, so I had to rebound. There were times I would bring it up the court and initiate the offense. I had the ball in my hands a lot, which was a good thing. As soon as I got over there, they accepted me right away and sort of knew that for us to win, I was going to have to be a big part of that team.”

Murphy continued his strong play in the actual tournament, leading the team with averages of 17.4 points, 6.6 rebounds, 1.4 assists, 1.3 blocks and 1.1 steals.

“The level of competition was good over there – it was better than I expected,” he said. “It’s hard to compare it to college. The style of game is different. I think it’s a more physical game … its chippy for sure.”

Murphy is convinced that the experienced helped prepare him for his season.

“I think that was the best thing I could have done this summer,” he said. “Not actually being on the court playing games for a year was tough. Just the feeling of being back out there playing in a game that meant something and mattered felt great and got me even more excited.”

Murphy will challenge for a starting job on Duke’s perimeter this season. If he continues to build on what he did last summer, he could be the big wing that the Blue Devils lacked a year ago.

“That’s what I want to be,” he said. “I think I can play multiple positions, but that’s what I do best. We call it a wing … having a big wing – that’s what Duke’s had in the past with guys like Kyle [Singler]. They talked to me about guys like [Shane] Battier, Mike Dunleavy – they were 6-8, 6-9 and could play multiple positions. They could do a lot of things.”

All three summer travelers will be primed to expand their roles this week when Duke opens preseason practice. Murphy will be challenging for a starting role on the wing; Cook expects to compete for the point guard job; and Marshall Plumlee expects to back up his older brother Mason and senior Ryan Kelly in the post.

“I feel like I have a good opportunity to bring some energy to the team and provide some depth to the post,” Plumlee said. “I’ve been working hard to become someone who’s easy to play with, somebody who can help rebound, defend … just help the team flow.”

Basketball is a winter game that decides its championship just as spring is blooming. But a busy summer overseas ought to help the 2012-13 Blue Devils enjoy a successful season.